From 9f786a2867183f61a076ed37b49db9b9e2c8fdeb Mon Sep 17 00:00:00 2001
From: David Roundy <droundy@darcs.net>
Date: Fri, 1 Jun 2007 19:50:42 +0200
Subject: improve changeMosaic.

darcs-hash:20070601175042-72aca-2fc051063bc744a4ecf322361e372473aad122c4.gz
---
 Mosaic.hs | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

(limited to 'Mosaic.hs')

diff --git a/Mosaic.hs b/Mosaic.hs
index fb8f544..2b1e96b 100644
--- a/Mosaic.hs
+++ b/Mosaic.hs
@@ -319,9 +319,17 @@ lengthM (M x) = sum $ map lengthM x
 
 changeMosaic :: Mosaic a -> [Mosaic a]
 changeMosaic (OM a) = []
-changeMosaic (M xs) = [makeM $ reverse xs] ++
-                      map makeM (concatenations xs) ++
-                      map makeM (splits xs) -- should also change the lower level
+changeMosaic (M xs) = map makeM (concatenations xs) ++
+                      map makeM (splits xs) ++
+                      map M (tryAll changeMosaic xs)
+
+tryAll :: (a -> [a]) -> [a] -> [[a]]
+tryAll _ [] = []
+tryAll f (x:xs) = map (:xs) (f x) ++ map (x:) (tryAll f xs)
+
+onceToEach :: (a -> a) -> [a] -> [[a]]
+onceToEach _ [] = []
+onceToEach f (x:xs) = (f x : xs) : map (x:) (onceToEach f xs)
 
 splits :: [Mosaic a] -> [[Mosaic a]]
 splits [] = []
-- 
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